[PATCH] nvme: use __iowrite64_copy for SQs in the CMB

[Saar Gross]

Hi again,

Any other comments?

Thanks,
Saar


On Wed, Nov 30, 2016 at 10:31 AM, Saar Gross <saar at annapurnalabs.com> wrote:
> Sorry for taking so long to reply: yes, it might help with some PCIe
> devices with weird alignment requirements.
>
> The patch itself doesn't fix any broken devices (possibly other than
> those PCIe devices mentioned above), it only replaces the current
> implementation of memcpy_toio() to __iowrite64_copy() which is more
> suited when working with WC buffers. We've tested the patch on a CMB
> enabled device where we got the same performance as the original
> implementation, which is expected as using __iowrite64_copy() should
> really only make a difference with a very stressed system.
>
> Thanks,
> Saar
>
>
> On Tue, Nov 22, 2016 at 4:43 AM, Stephen Bates <sbates at raithlin.com> wrote:
>>
>>>>
>>>> Any comments on this patch? I didn't receive any so far.
>>>>
>>>
>>> Please explain why we would want to apply the patch, e.g. without
>>> it some devices may be broken, or that on a particular device you get much
>>> better performance (including numbers and an explanation of the setup).
>>>
>>
>> Some PCIe devices have requirements on the alignment of PCIe writes into
>> them. Would this patch help with some of those devices?
>>
>> Stephen
>>